Doing this in our cross-toolchain case results
in /usr/include getting included directly, which
we do not want as it breaks cross.

--- a/compiler-rt/lib/orc/CMakeLists.txt
+++ b/compiler-rt/lib/orc/CMakeLists.txt
@@ -50,11 +50,6 @@ include_directories(../../include)
 
 set(ORC_CFLAGS ${COMPILER_RT_COMMON_CFLAGS})
 
-# Allow the ORC runtime to reference LLVM headers.
-foreach (DIR ${LLVM_INCLUDE_DIR} ${LLVM_MAIN_INCLUDE_DIR})
-  list(APPEND ORC_CFLAGS -I${DIR})
-endforeach()
-
 add_compiler_rt_component(orc)
 
 # ORC uses C++ standard library headers.
